Administration grounded all US flights Friday afternoon, due to “extraordinary circumstances and for reasons of safety,” the agency said in a statement. Flights already in the air will be allowed to land, the agency said, but no new ones are permitted to take off.
In a post on X, US Transportation Secretary Sean Duffy said that the ground stop was related to a communication issue affecting Air Traffic Control Centers, and said that agency technicians are investigating.
The ground stop came after widespread reports of radio frequency outages among several of the nation’s most critical Air Traffic Control Centers, including in Boston, Chicago, and New York. Air traffic controllers use designated radio frequencies to communicate with pilots and manage and monitor airspace safety. In the past, controllers have used voice communications relayed over these radio frequencies to direct traffic; in recent years, the FAA has also rolled out a text-based communication system.
Reached for comment, an FAA spokesperson did not provide any additional details.
Nationwide ground stops are rare. The FAA halted all air traffic on September 11, 2001. In January of 2023, a ground stop was issued after an outage to a critical system that the FAA used to distribute real-time data and warnings to pilots, known as NOTAM (Notice to Air Mission).
“This really points to how much we need to modernize our air traffic control system,” says Susan Hotle, a professor of transportation engineering at Virginia Tech who worked at the FAA. “Right now all it takes is for one system to go out, and it affects a wide region at once.”
Earlier Friday, Duffy wrote congressional leaders to ask lawmakers to “act swiftly” on the Transportation Department’s request for $30.1 billion funding updates to the nation’s air traffic control system.
If the outage lasts more than a couple hours, it will take airlines—and the flyers that depend on them—days to recover, says Michael McCormick, a professor at Embry-Riddle Aeronautical University and a former air traffic controller. An extended stop would mean “airline systems are going to be complete in chaos, with aircraft and air crews in the wrong places. It would take days to get up and back running normally,” he says.
The FAA said this week that it was rolling out a new AI tool to help advise air traffic controllers. The tool, now available nationwide, had been tested in the busy Washington, DC, region. There is no evidence to suggest today’s ground stop is related to this new tool.
At San Francisco International Airport on Friday, hoards of confused travelers lined up to speak with airline staff. A number flights at the airport had already been delayed because of high winds, and the FAA ground stop was now compounding the issue.
“The FAA has issued a nationwide ground stop,” a United Airlines employee said over the intercom at Terminal 3 near the E departure gates. “This is a nationwide event.”
This is a developing story. Please check back for updates. Louise Matsakis contributed reporting.